Figure 1 – General habit of L. inermis. Photo by S. Sanogo, IER.
Taxonomy and Nomenclature
Synonyms. Lawsonia speciosa L., L. spinosa L.
Vernacular / Common Names. Henna (English); henné, réséda de France (French); djabi (Bambara); pouddi (Peul).
Life form. Shrub or tree.
Plant. Evergreen, 2–7 m tall (Figure 1), glabrous, branches often densely tangled, young branches 4-angular, becoming terete, rigid, often spinescent, spines <3.5 cm long . leaves. Elliptic, obovate to oblanceolate, c. 1–6.5 x 0.5–2.5 cm, apex acute or mucronate, petiole short.
Flowers. Panicles 5–25 cm long, flowers creamy white, scented, petals c. 2 mm long, slightly clawed .
Fruits and Seeds
Spherical, indehiscent, glabrous capsules (Figure 2), with the calyx at the base and the persistent style at the top, c. 5 mm in diameter, pale brown when ripe, containing numerous pyramidal seeds (Figure 3) .
Flowering and fruiting. Flowers in the second half of the dry season and at the start of the rainy season in the Sikasso region of Mali.
Native to western tropical Asia, North Africa and probably the eastern coast of Africa; widely introduced, naturalised and cultivated throughout the tropics .
Temporarily flooded, rocky watercourses in dry areas, riverine thickets and forest, bushland, cliffs and rocky crevices, up to 1,400 m a.s.l. . It is often found on alluvial soils along rivers and in villages , and also prefers sandy soils . It is thought to have been cultivated in Sudano-Sahelian areas since prehistory .
Henna is one of the world’s oldest cosmetics. The dye from its leaves is used to decorate hands (Figure 4), nails, feet and hair, and is also used to colour leather and clothes.
Figure 2 – Ripening fruits. Photo by S. Sanogo, IER.
Figure 3 – External views of the seeds. Photo by P. Gómez-Barreiro, RBG Kew.
Figure 4 – Hand decorated with henna. Photo by R. Dackouo, IER.
Written records of use date back more than 2,500 years: henna was used in Ancient Egypt  and is mentioned in the Bible. Subsequently, henna assumed great importance in Islam (it is used in many ceremonies, especially marriage), Hinduism and Buddhism. In traditional medicine, henna is used as a panacea in the treatment of many diseases [5,6]. The roots are used as a diuretic, to promote childbirth, and to treat gonorrhoea and bronchitis. The leaves have antibiotic properties and are used to treat leprosy and scurvy. A decoction of the leaves and roots is used to treat diarrhoea. A perfume is made from the flowers. The wood is used in India for making stakes and handles, and also provides firewood. Henna is used for soil conservation; and is widely planted as a living fence and as an ornamental . The flowers attract bees .
Known Hazards and Safety
Generally considered to be safe but should not be used by those with glucose-6-phosphate dehydrogenase (G6PD) deficiency . Allergic reactions are rare. However, adulterants added to henna paste, or products sold as substitutes for henna that contain para-phenylene diamine (PPD) (e.g. black henna), can sometimes cause severe allergic reactions . Care should be taken when handling the plant as the spines on the stems are sharp.
This widespread species is not considered to be either rare or threatened. It has been assessed as Least Concern (LC) in West Africa  and Sri Lanka according to IUCN Red List criteria , but its status has yet to be confirmed in the IUCN Red List .
Harvesting. Ripe fruits can be collected directly from the plants.
Processing and handling. Seeds can be extracted by hand from the dry capsules.
Storage and viability. Seeds are reported to be orthodox . Therefore, after appropriate drying, they can be stored at sub-zero temperatures for long-term conservation.
Dormancy and pre-treatments: Seeds of this species are reported to be physiologically dormant . Soaking the seeds in water for 1–3 days promotes germination . Seed lots stored at the MSB were incubated without any pre-treatments, or by adding potassium nitrate (KNO3) to the germination substrate. High germination percentages were achieved in both cases .
Germination, sowing and planting: Under laboratory controlled conditions, untreated and KNO3-treated seeds stored at the MSB reached high germination percentages when incubated in the light at constant temperatures of 20–26 degrees C or under alternating temperature regimes of 15/25 degrees C and 20/35 degrees C . In the nursery, germination takes 2–3 weeks after sowing, with a germination rate of up to 70% .
Vegetative propagation. Easy to propagate from cuttings . Micropropagation is also reported to be successful ; a protocol for mass propagation has been developed .
Trade. No trade statistics are available for Mali. Large quantities of henna are produced at home or for local markets, so accurate estimates of international production.
More from Wild Plants for a Sustainable Future:
Cover courtesy of The Royal Botanic Garden, Kew
Excerpted with permission from Wild Plants for a Sustainable Future: 110 Multipurpose Species, edited by Tiziana Ulian, Cesar Flores, Rafael Lira, Avhatakali Mamatsharaga, Kebadire K. Mogotsi, Patrick Muthika(t), Samodino Ngwako, Desterio O. Nyamongo, William Omondi, Abdoul K. Sanogo, Sidi Sanogo and Efisio Mattana. Published by the Royal Botanic Gardens, Kew, and distributed by University of Chicago Press, 2019. © The Board of Trustees of the Royal Botanic Gardens, Kew